As the demand for use of Voice over Internet Protocol (VoIP) across the public Internet increases, the ability to provide Emergency 911 (E911) calling features has been problematic. With traditional landlines, the landlines are typically statically installed and mapped to a particular physical address. Thus, a subscriber of the landline telephone system could call E911 services and, in most instances, the emergency dispatcher would have access to the physical address of the subscriber and the ability to send the appropriate emergency personnel to that physical address.
However, as many more subscribers are using VoIP technology as a replacement for traditional landline telephones in their homes, the ability for emergency dispatchers to pinpoint the physical address of the subscriber has become more difficult. For example, unlike traditional landline telephone subscribers, VoIP subscribers are not tied to their Internet Service Provider (ISP). Thus, VoIP subscribers can change ISPs often. For example, a subscriber may plug their telephone adapters (TAs) into a totally different ISP network, synchronize to the VoIP gateways through that ISP network and start receiving calls almost immediately. This can make it very difficult to determine the physical location of the subscriber.
Recently, the Federal Communications Commission (FCC) mandated that all VoIP Service Providers provide E911 services. This is currently accomplished by having the VoIP subscriber provide their current physical address when signing up for the service. Using the physical address provided by the subscriber, the Service Provider can statically map the subscriber to an appropriate Public Safety Answering Point (PSAPs). PSAPs are the locally/regionally assigned E911 call centers that can redirect calls or dispatch emergency personnel to the appropriate locations.
A problem with the current system using static mapping of the provided physical address is the ability of subscribers to change ISPs and/or locations without informing the service provider and still have a working VoIP telephone. In other words, subscribers do not necessarily have to remain at their registered addresses. Furthermore, network connectivity may also be a problem with the current system. In particular, VoIP packets are communicated through the public Internet and voice packets are not necessarily given a higher priority over other data traffic. Thus, calls to E911 PSAPs may not be guaranteed to ever reach their destination Finally, the local broadband connectivity to the ISP may be offline, for example, the digital subscriber line (DSL) or cable modem may not be connected to the network.